This invention relates to compositions for preparing polymer concrete useful for the protection or reconditioning of surfaces and for other applications.
A polymer concrete (sometimes abbreviated herein as "PC") is a composite material formed by polymerizing a monomer in admixture with an aggregate, wherein the polymerized monomer operates as a binder for the aggregate. These materials are to be distinguished from a polymer-impregnated concrete and from polymer-portland cement concrete. The former is a precast portland cement concrete subsequently impregnated with a monomer which is polymerized in situ, and the latter is a premixed material wherein either a monomer or polymer is added to a fresh concrete mixture in a liquid, powdery or dispersed phase, and subsequently polymerized (if needed) and cured. PC materials, as contrasted with polymer-portland cement concrete, are prepared from substantially non-aqueous compositions.
PC compositions, as well as the related polymer-impregnated concrete and polymer-portland cement concrete compositions, are reviewed in Chemical, Polymer and Fiber Additives for Low Maintenance Highways, edited by G. C. Hoff et al, Chemical Technology Review No. 130, Noyes Data Corporation, Park Ridge, N.J. 1979, particularly Chapter 10, "Polymers In Concrete," pages 430-479. Another review is Chemical Materials for Constructions, Phillip Maslow, Structures Publishing Company, Farmington, Mich., 1979, particularly Chapter 4, "Epoxies With Concrete", pages 280-340. Representative patents concerning polymer concrete materials are U.S. Pat. Nos. 4,500,674--Fontana et al and 4,460,625--Emmons et al.
Typically, a composition for preparing a polymer concrete is a substantially non-aqueous slurry of an aggregate, a monomer binder system and a polymerization catalyst. These components are often packaged separately and mixed on-site, to avoid premature polymerization. Among the monomers used as binders are low viscosity monomers such as methyl methacrylate and styrene used singly or in admixture, and sometimes with other monofunctional monomers or with polyfunctional monomers such as trimethylol propane trimethacrylate. Polyester-styrene, furan, vinyl ester and epoxy resins and oligomers have also been used in preparing polymer concretes, in each case in combination with suitable catalysts for initiating and/or accelerating the curing of the compositions.
Generally, polymer concrete compositions exhibit substantially greater compressive strength, flexural strength and durability (chemical resistance), and essentially zero permeability to liquids, as compared with portland cement concrete. Despite such advantages, the known polymer concrete compositions tend to shrink unduly during hardening, cure either too slowly or with difficulty (often because of inhibition from ambient oxygen), and present environmental hazards because of volatile organic components.